This invention generally relates to a method and system for monitoring a pressurized container. More particularly, the present invention relates to a monitoring system for a pressurized container that includes a safety device or an information providing device.
Containers, such as, for example, systems, piping, or tanks, that contain a fluid that is pressurized or that may be pressurized often include pressure reduction equipment that is designed to ensure the safety of the container and/or to provide information about the operation of the system. This pressure reduction equipment may include, for example, pressure relief devices, pressure release devices, pressure control systems, pressure indicating devices, pressure driven switching devices, temperature indicating devices, fluid pH level indicating devices, and vibration indicating devices.
Pressure relief devices are commonly used as safety devices to prevent fluid containers from experiencing potentially hazardous over-pressure or under-pressure conditions. The pressure relief devices are designed to activate, or open, when the pressure of the fluid within the container reaches a predetermined pressure limit that is indicative of an over-pressure condition. The activation of the pressure relief device creates a vent path through which fluid may escape to relieve the over-pressure situation in the pressurized container.
A pressure relief device, which may include, for example, rupture disks, pressure relief valves, pressure safety valves, control valves, butterfly valves, gate valves, globe valves, diaphragm valves, buckling pin devices, tank vents, explosion panels, or other such devices, may be connected to the container so that at least a portion of the pressure relief device is exposed to the fluid within the container. When the fluid reaches or exceeds the predetermined pressure limit, the force of the fluid on the pressure relief device acts on the pressure relief device to activate the pressure relief device, thereby creating an opening. Fluid may then escape from the container through the opening to relieve the over-pressure condition.
Pressure release devices are commonly used to allow the movement of a pressurized fluid from one container to another container or system. The pressure release devices, which may be, for example, control valves, butterfly valves, gate valves, globe valves, ball valves, diaphragm valves, or other such devices, are connected to the container so that at least a portion of the pressure release device is exposed to the fluid within the container. The pressure release devices are designed to activate, or open, on demand. This activation can be manual or automatic, based upon the requirements of the user. When fluid is required to be discharged from the container, the pressure release device may be activated to create an opening. The activation of the pressure release device creates a vent path through which fluid may escape from the pressurized container.
A combination of different types of pressure reduction equipment may be included in a container. For example, a pressure relief device may be engaged with the system to provide protection from an over pressure situation within the particular container. A pressure release device may be engaged with the container to allow the discharge of fluid from the container upon the command of an operator or an appropriate automatic sensing system when certain internal or external conditions are experienced that warrant discharge of the pressurized fluid from the container.
Each pressurized container is designed to withstand a maximum allowable working pressure. If the pressure of the fluid within the container were to exceed this maximum allowable working pressure without activation of the pressure reduction device, the container could become unsafe. To ensure that the pressure of the container does not exceed the maximum allowable working pressure and the relevant design code permitted overpressure, a pressure reduction device that is configured to activate at a pressure that is within a certain tolerance (e.g. 105%) of the maximum allowable working pressure may be engaged in the container.
Ensuring that the pressure reduction equipment activates at the rated pressure, or within a manufacturing tolerance of the rated pressure, is of great importance. If the pressure reduction device activates at a pressure that is higher than the rated pressure, the fluid pressure may exceed the maximum allowable working pressure. If the pressure reduction device activates at a pressure that is lower than the rated pressure, the activation may interfere with the normal operation of the system and could potentially result in the premature loss of fluid from the system.
The pressurized containers may further include a pressure control system that is designed to prevent the pressurized container from experiencing potentially hazardous over-pressure or under-pressure conditions. These pressure control systems monitor the pressure of the fluid within the container. When the fluid pressure approaches a predetermined pressure limit that is indicative of an impending over-pressure or under-pressure condition, the pressure control system may activate a control device, such as, for example, a control valve that injects a chemical reaction agent, catalyst, quenching agent, or stabilizer into the working fluid. The activation of the pressure control system may thereby avoid the need to create a vent path to reduce the pressure of the fluid in the pressurized system. Alternatively, the pressure control system may activate a pressure release device, such as, for example, a butterfly valve, a ball valve, or a globe valve, to release fluid in a sufficient quantity to avoid or limit the over-pressure or under-pressure condition. Thus, the control system may automatically handle the opening and closing of a vent path in a pressure release device to reduce the pressure within the container.
The pressurized containers may use a combination of pressure control devices and pressure reduction devices. These pressure control devices monitor the pressure of the fluid within the container. When the fluid pressure reaches a level that may be too low or too high for the proper function of the pressure release device, the pressure control system may activate an annunciation system to alert the user to the improper operating condition of the pressurized container. A pressure relief device may additionally be used to provide automatic release of fluid in a sufficient quantity to avoid or limit an overpressure or under-pressure condition.
The pressurized containers may also include a pressure indicating device that identifies the depletion of the fluid within the container. These pressure indicating devices can be used to prevent the containers from experiencing potentially low or high pressure conditions that might inconvenience the user. The pressure indicating devices are designed to trigger a response, such as the opening of a supply valve, when the pressure of the fluid within the system reaches a predetermined low pressure limit that is indicative of the fluid becoming depleted. Such pressure indication can also trigger a response when the pressurized container is reaching a potentially damaging vacuum condition.
The pressurized containers may further include a pressure indicating device that identifies the increase in quantity of the fluid within the container. These pressure indicating devices can prevent the containers from experiencing potentially high pressure conditions that might damage the container. The pressure indicating devices are designed to trigger a response, such as, for example, the opening or closing of a supply valve, when the pressure of the fluid within the system reaches a predetermined pressure limit that is indicative of the system becoming filled with fluid.
It has been found that the operating conditions of the fluid container, such as, for example, the temperature and pressure of the fluid, may have an impact on the operation of the above-described pressure reduction devices and information providing devices that may be engaged with the container. For example, the operating conditions of the container may have an impact on the pressure at which a pressure relief device activates. In some situations, the operating conditions of the container may cause the pressure relief device to activate at a pressure that is lower than expected. In other situations, the operating conditions of the container may cause the pressure relief device to activate at a pressure that is higher than expected.
In a container that uses a rupture disk as a pressure relief device, the temperature of the fluid in the container may impact the pressure at which the rupture disk will activate. The activation pressure of the rupture disk is determined, in part, by the physical properties of the material used to form to the rupture disk. Excessive heat or excessive cold may alter the physical properties of the material, thereby altering the activation pressure of the rupture disk. Other operating conditions, such as, for example, pressure fluctuations, pressure levels, vibration frequencies and amplitudes, and acidity levels could also have an impact on the activation pressure of the rupture disk or other such pressure relief device.
Similarly, the operating conditions of the container may also impact the operation of a pressure release device, a pressure control device, and/or a pressure indicating device. For example, excessive pressures or temperatures may impact the ability of a pressure control device to deliver a stabilizing agent to a chemical reaction process before an over-pressure condition is reached. In addition, the operating conditions may prevent a pressure indicating device from providing accurate pressure indications.
Early identification of an operating condition that may impact the operation of a pressurized container fluid system or an associated pressure release devices, pressure relied device, and/or pressure control device may allow an operator to take corrective action. For example, the affected device could be repaired or replaced after experiencing a potentially problematic operating condition. In this manner, the reliability of the pressurized container fluid system and the associated safety and informational systems could be maintained.
In light of the foregoing, there is a need for a method and system for monitoring the operating conditions experienced by a pressurized container to identify conditions that may have an impact on the operation of a pressure reduction device, a pressure control system, and/or an information providing device that is engaged with the container.